

Note that the eigenvalues of matrix \({{{\bf Q}}^{-1}{\bf B}}\)  are subjected to the Grenander–Szegö's theorem [1]}; i.e.,
\(\min \frac{p_{{\alpha } }({\theta } )}{q_{{\alpha } }({\theta } )}\le \lambda _{\min }({{\bf Q}}^{-1}{\bf B})\le \lambda _{\max }({{\bf Q}}^{-1}{\bf B})\le \max \frac{p_{{\alpha } }({\theta } )}{q_{{\alpha } }({\theta } )}.\) 
